CVE-2025-66418

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Source
https://cve.org/CVERecord?id=CVE-2025-66418
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66418.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2025-66418
Aliases
Downstream
Related
Published
2025-12-05T16:02:15.271Z
Modified
2026-08-05T03:32:24.251148239Z
Severity
  • 8.9 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H CVSS Calculator
Summary
urllib3 allows an unbounded number of links in the decompression chain
Details

urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

Database specific 
{
    "cwe_ids": [
        "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66418.json",
    "cna_assigner": "GitHub_M",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "introduced": "1.24"
                },
                {
                    "fixed": "2.6.0"
                }
            ],
            "source": "AFFECTED_FIELD"
        }
    ]
}
References

Affected packages

Git / github.com/urllib3/urllib3

Affected ranges

Type
GIT
Repo
https://github.com/urllib3/urllib3
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
24d7b67eac89f94e11003424bcf0d8f7b72222a8
Database specific 
{
    "source": "REFERENCES"
}

Affected versions

0.*
0.3
0.3.1
0.4
0.4.1
1.*
1.1
1.2
1.2.1
1.25
1.25.1
1.25.2
1.25.3
1.25.4
1.25.5
1.25.6
1.25.7
1.25.8
1.3
1.4
1.5
1.6
1.7
1.7.1
2.*
2.0.0
2.0.0a1
2.0.0a2
2.0.0a3
2.0.0a4
2.0.1
2.0.2
2.0.3
2.0.4
2.0.5
2.0.6
2.1.0
2.2.0
2.2.1
2.2.2
2.2.3
2.3.0
2.4.0
2.5.0
v2.*
v2.0.5

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66418.json"